.big{
    width: 100% !important;
    display: inline-block;
}


.nav1 {
    width: 100%;
    height: 60px;
    margin-bottom: -100px;
}

.container
		{
			width: 100%;
			margin: 5px auto;
		}
.item {
    box-sizing: border-box;  /*border计算在width中*/
    -moz-box-sizing:border-box; /* Firefox */
    -webkit-box-sizing:border-box; /* Safari */
    width: 25%;
    height: 150px;
    border:1px solid #cccccc;
    float:left;
    text-align: left;
}

.container:after{
    display: block;
    clear: both;
    content: ".";
    height: 0;
    visibility: hidden;
    display: block;
}

